实现Callable接口。带返回值的线程

public class Main implements Callable{
    int i;
    @Override
    public Object call() throws Exception {
        String str=null;
        for (i=0;i<100;i++){
            str=Thread.currentThread().getName()+"--"+i;
            System.out.println(str);
        }
        return str;
    }
}

public class Client {
    public static void main(String[] args) {
        ExecutorService threadPool= Executors.newSingleThreadExecutor();
        Future<String> future=threadPool.submit(new Main());
        System.out.println("----------");
        try {
            System.out.println(future.get());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }
}